Methods and Apparatus for Distributed Baseband Signal Processing for Fifth Generation (5G) New Radio Downlink Signals

ABSTRACT

Methods and apparatus for baseband signal compression of fifth generation new radio downlink signals. In an embodiment, a method includes receiving compressed packets over a transmission medium from a central office that performs a first portion of baseband processing to generate the compressed packets from downlink data, receiving configuration parameters, performing a second portion of baseband processing to decompress the compressed packets using the configuration parameters to generate the downlink data, and transmitting the downlink data. An apparatus includes an interface that receives compressed packets and configuration parameters over a transmission medium from a central office that includes a first baseband processing section that generate the compressed packets from downlink data. The apparatus also includes a second baseband processing section that decompresses the compressed packets using the configuration parameters to extract the downlink data, and a radio frequency (RF) interface that transmits the downlink data.

CLAIM TO PRIORITY

This application claims priority from U.S. Provisional Application No.62/849,029, filed on May 16, 2019, and entitled “METHOD AND APPARATUSFOR BASEBAND SIGNAL COMPRESSION OF 5G NR DOWNLINK,” which isincorporated by reference herein in its entirety.

FIELD

The exemplary embodiments of the present invention relate to operationof telecommunications networks. More specifically, the exemplaryembodiments of the present invention relate to receiving and processingdata streams for use in wireless telecommunication networks.

BACKGROUND

With a rapidly growing trend of mobile and remote data access over ahigh-speed communication networks, such as Long Term Evolution (LTE),fourth generation (4G), and fifth generation (5G) wireless networks,accurately delivering and deciphering data streams become increasinglychallenging and difficult.

During downlink operation, baseband signals at a central office need tobe transmitted to remote sites for transmission to user equipment.Typically, wireless operators utilize leased data lines to transmitinformation between the central office and the remote sites. It isdesirable to use these leased lines as efficiently as possible to allowthe use of less expensive lines or allow the transmission of more 5Gchannels using the existing lines.

Therefore, it is desirable to have a system that enables efficienttransmission of downlink baseband signals from a central office toremote sites.

SUMMARY

In various exemplary embodiments, a downlink transmission systemcomprising methods and apparatus are provided for transmission ofdownlink signals from a central office to remote sites. In anembodiment, a primitive downlink baseband signal vector is defined foreach resource block as beam (or antenna) index/gain, index/modulation,or order/modulation data. In an embodiment, a 5G NR symbol (OFDMAsymbol) is compressed with a packet comprising multiple primitive datavectors and transferred from the baseband signal processor in thecentral office to the remote radio head at the antenna site. Byutilizing a downlink baseband front-end and decompressor (symbolmapper+beamformer), the remote radio head can successfully decompressthe downlink baseband signal information to the time domain sequences,which is directly upshifted and transferred via transmit antennas.

The various embodiments are fully compliant with 5G NR standards withoutadding any other side information, provide ultra-low latency since therequired procedures are straightforward and don't include time-consumingor complicated signal processing, and provide computation power savingsat the central office by offloading downlink signal processing to remotesites.

In an embodiment, a method is provided that includes receivingcompressed packets over a transmission medium from a central office thatperforms a first portion of baseband processing to generate thecompressed packets from downlink data, receiving configurationparameters, performing a second portion of baseband processing todecompress the compressed packets using the configuration parameters togenerate the downlink data, and transmitting the downlink data.

In an embodiment, an apparatus is provided that includes an interfacethat receives compressed packets and configuration parameters over atransmission medium from a central office that includes a first basebandprocessing section that generate the compressed packets from downlinkdata. The apparatus also includes a second baseband processing sectionthat decompresses the compressed packets using the configurationparameters to extract the downlink data, and a radio frequency (RF)interface that transmits the downlink data.

Additional features and benefits of the exemplary embodiments of thepresent invention will become apparent from the detailed description,figures and claims set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

The exemplary aspects of the present invention will be understood morefully from the detailed description given below and from theaccompanying drawings of various embodiments of the invention, which,however, should not be taken to limit the invention to the specificembodiments, but are for explanation and understanding only.

FIG. 1 shows a block diagram of a communication network that includes anexemplary embodiment of a distributed downlink baseband processingsystem.

FIG. 2 shows an exemplary detailed embodiment of a central office andremote site shown in FIG. 1.

FIG. 3 shows an exemplary compressed downlink data packet generated byan embodiment of a first baseband processing section and decompressed byan embodiment of a second baseband processing section.

FIG. 4 shows an embodiment of a compression format for each resourceblock of downlink subcarrier data.

FIG. 5 shows a detailed embodiment of the baseband processing section(B) that comprises the downlink decompressor shown in FIG. 2.

FIG. 6 shows an exemplary embodiment of the downlink front end shown inFIG. 5.

FIG. 7 illustrates how embodiments of the distributed downlink basebandprocessing system transmits downlink signals from a central office to aremote site with greater efficiency than conventional systems.

FIG. 8 shows an exemplary method for performing downlink basebandcompression in accordance with exemplary embodiments of a distributeddownlink baseband processing system.

DETAILED DESCRIPTION

Aspects of the present invention are described below in the context ofmethods and apparatus for compression of 5G new radio downlink signals.

The purpose of the following detailed description is to provide anunderstanding of one or more embodiments of the present invention. Thoseof ordinary skills in the art will realize that the following detaileddescription is illustrative only and is not intended to be in any waylimiting. Other embodiments will readily suggest themselves to suchskilled persons having the benefit of this disclosure and/ordescription.

In the interest of clarity, not all of the routine features of theimplementations described herein are shown and described. It will, ofcourse, be understood that in the development of any such actualimplementation, numerous implementation-specific decisions may be madein order to achieve the developer's specific goals, such as compliancewith application and business related constraints, and that thesespecific goals will vary from one implementation to another and from onedeveloper to another. Moreover, it will be understood that such adevelopment effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking of engineering for those ofordinary skills in the art having the benefit of embodiments of thisdisclosure.

Various embodiments of the present invention illustrated in the drawingsmay not be drawn to scale. Rather, the dimensions of the variousfeatures may be expanded or reduced for clarity. In addition, some ofthe drawings may be simplified for clarity. Thus, the drawings may notdepict all of the components of a given apparatus (e.g., device) ormethod. The same reference indicators will be used throughout thedrawings and the following detailed description to refer to the same orlike parts.

The term “system” or “device” is used generically herein to describe anynumber of components, elements, sub-systems, devices, packet switchelements, packet switches, access switches, routers, networks, modems,base stations, eNB (eNodeB), computer and/or communication devices ormechanisms, or combinations of components thereof. The term “computer”includes a processor, memory, and buses capable of executing instructionwherein the computer refers to one or a cluster of computers, personalcomputers, workstations, mainframes, or combinations of computersthereof.

FIG. 1 shows a block diagram of a communication network 100 thatincludes an exemplary embodiment of a distributed downlink basebandprocessing system. The network 100 may operate as a fourth generation(“4G”), Long Term Evolution (LTE), Fifth Generation (5G), New Radio(NR), or combination of 4G and 5G cellular network configurations.

The network 100 includes a central office 120 and remote site 104 thatcommunication with each other using transmission lines 118. In anembodiment, the central office 102 and remote site 104 are separated bya large distance. The transmission lines 118 are optical fiber or othersuitable transmission medium.

In an embodiment, the central office 102 comprises a baseband processingsection (A) 120 that performs first portion of baseband processing tocompress and transmit compressed downlink baseband packets 112 to theremote site 104 using the transmission lines 118. In an embodiment, thebaseband processing section (A) 120 also generates configurationparameters 114 that are transmitted to the remote site 104 using thetransmission lines 118. The configuration parameters 114 describe how todecompress the compressed downlink packets 112.

The remote site 104 comprises baseband (BB) processing section (B) 106and an RF interface 108. The RF interface 108 transmits downlinkcommunications to user equipment, such as user equipment 116, usingantenna 110. The RF interface 108 receives the downlink communicationsfrom the baseband processing section 106. The BB processing section 106performs a second portion of baseband processing to receive anddecompress the compressed downlink packets 112 according to the receivedconfiguration parameters. The decompressed downlink packets are providedto the RF interface for transmission to user equipment.

Thus, the network 100 illustrates a distributed baseband processingsystem that efficiently utilizes transmission lines between the centraloffice 102 and the remote site 104. The baseband processing section (A)120 performs a first portion of the baseband processing to compress andtransmit downlink packets and configuration parameters to the remotesite 104. The remote site 104 performs a second portion of the basebandprocessing to receive and decompress the compressed packets 112according to the received configuration parameters 114 to generatedownlink packets for transmission to user equipment. The compressedpackets 112 contain downlink data in compressed format without loss toefficiently utilize the transmission lines 118, thereby allowing the useof less expensive transmission line or to allow more channels ofinformation to be transmitted over existing transmission lines. A moredetailed description of the distributed baseband processing system isprovided below.

FIG. 2 shows an exemplary detailed embodiment of a central office 102and remote site 104 shown in FIG. 1. In an embodiment, the centraloffice 102 includes one or more baseband (BB) DSPs, such as DSP 202,that are part of the BB processing section (A) 120. The central office102 also includes an interface 204 that transmits and receivesinformation over transmission lines 118. In an embodiment, the DSPs,such as DSP 202, compress downlink baseband packets and transmit thesepackets 112 to the remote site 104 using transmission lines 118. TheDSPs also transmit the configuration parameters 114 to the remote site104 using the interface 204 and transmission lines 118. In variousembodiments, any type of packetized transmission format can be utilized.The configuration parameters 114 describe how the compressed downlinkpackets 112 are to be decompressed.

The remote site 104 includes an interface 206 that receives thecompressed downlink packets 112 and the configuration parameters 114 andpasses this information to a downlink de-compressor 208 that is part ofthe BB processing section (B) 106. The decompressor 208 decompressesdownlink packets 112 according to the configuration parameters 114 andpasses the decompressed downlink packets 218 to one or more RFinterfaces, such as RF interface 108. For example, each RF interfacereceives downlink packets for transmission using antennas, such asantenna 110, and converts the received digital downlink packets to ananalog signal format using digital-to-analog (DAC) converters. Thus, theRF interfaces generate analog downlink signals that are transmitted bythe antennas 110 to user equipment.

FIG. 3 shows an exemplary compressed downlink data packet 300 generatedby an embodiment of the first baseband processing section 120 anddecompressed by an embodiment of the second baseband processing section106. During operation, the baseband processing section 120 generates thedata packet 300 for each antenna. The data packet 300 includes a header302 that comprises an antenna index, packet time stamp, and a(frame:slot:symbol number), which identifies the packet. The data packet300 also includes downlink frontend configuration parameters 304 thatare provided when necessary. The data packet 300 also includessubcarrier data 306 that comprise modulation order and transmit data. Inan embodiment, the generated data packets 300 can be transmitted fromthe central office 102 to the remote site 104 in any order.

Configuration Parameters

In an embodiment, the following is a non-exhaustive list ofconfiguration parameters 304. It should be noted that in otherembodiments, other configuration parameters may be utilized.

1. Antenna index2. FFT size3. Number of resource blocks4. Subcarrier spacing5. Cyclic prefix size6. Cyclic delay diversity offset7. Phase rotation8. Antenna calibration on/offset9. Antenna gain10. Subcarrier shift11. Beamformer matrix

FIG. 4 shows an embodiment of a compression format for each resourceblock of the subcarrier data 306. For example, the compression formatincludes a group descriptor 402, beam index/antenna index 404, gainindex 406, modulation order 408, and a plurality of symbols 410. In anembodiment, the group descriptor 402 has a values of zero or 1 where azero means empty and a 1 means normal traffic. The beam index/antennaindex 404 has a range between [0-(n−1)], which represents a beam orantenna index value. The gain index 406 has a range between [0-(n−1)],which represents a gain index identified in a predefined gain table. Themodulation order 408 has a value that represents modulation from BPSK to256 QAM. Each of the symbols 410 comprise m-bit binary data.

FIG. 5 shows a detailed embodiment of the baseband processing section(B) 106 that comprises the downlink decompressor 208 shown in FIG. 2. Inan embodiment, the decompressor 208 comprises gain table 502, symbolmapper 504, multiplier 506, and vector processor or multiplier 508. Thesymbol mapper 504 receives the symbol data 410 and maps them accordingto the modulation order 408. The mapped symbols are input to themultiplier 406 that adjusts the gain based on an output from the gaintable 502. The gain index 406 is used to access the gain table 402. Thegain adjusted symbols output from the multiplier 506 along with the beamindex/antenna index 404 are input to the vector multiplier 508, whichperforms one of beamforming or antenna mapping functions to generatefrequency domain baseband samples 510 to be transmitted. The frequencydomain samples 510 are input to one or more frontends, such as front end512, which use the frontend configuration parameters 304 to generatetime domain samples 514 that are input to RF interfaces (e.g., 108)where the time domain samples are converted to analog signals fortransmission by transmit antennas (e.g., 110). In various embodiments,the time domain antenna samples are transmitted using one of a 4G, 5G,or Wi-Fi transmission formats.

FIG. 6 shows an exemplary embodiment of the downlink front end 512 shownin FIG. 5. In an embodiment, the front end 512 comprises an antennacalibration and scaling circuit 602, subcarrier mapping circuit 604, andinverse Fourier transform circuit 606. The front end 512 also includes atime domain measurement circuit 608. In an embodiment, the frequencydomain baseband samples 510 output from the decompressor 208 arereceived by the calibration and scaling circuit 602, which performscalibration and/or scaling function. An output of the circuit 602 isinput to the subcarrier mapping circuit 604, which maps subcarriers. Anoutput of the mapping circuit 604 is input to the inverse Fouriertransform circuit 606, which also adds a cyclic prefix (CP) to generatethe time domain baseband samples 514 for transmission.

FIG. 7 illustrates how embodiments of the distributed basebandcompression system transmit downlink signals from a central office to aremote site with greater efficiency than conventional systems. FIG. 7shows a conventional downlink processing system 702 in which basebandsignals are processed at a central office 706 and transmitted overtransmission lines 118 to a remote site 704. All of the basebandprocessing is performed at the central office so that the transmissionlines 118 must carry low efficiency downlink baseband information. Forexample, transmission parameters and data computed at the central office706 are transmitted to the remote site over the transmission lines 118,which results in low efficiency transmission of information.

In contrast, the distributed baseband compression system 100 operates toperform a first portion of baseband processing at the central office102. For example, the BB processing section (A) performs a first portionof the baseband processing at the central office 102, and the BBprocessing section (B) performs a second portion of the basebandprocessing at the remote site 104. Since a portion of the basebandprocessing is performed at the remote site 104, the system 100 generateshigh efficiency compressed baseband packets at the central office thatare transmitted over the transmission lines 118 to the remote site 104where additional baseband processing is performed. Thus, thetransmission lines 118 are more efficiently utilizes by embodiments ofthe system 100.

FIG. 8 shows an exemplary method for performing downlink basebandcompression in accordance with exemplary embodiments of a downlinktransmission system. For example, the method 800 is suitable for usewith the downlink transmission system shown in FIG. 2.

At block 802, baseband symbols in resource blocks are compressed. Forexample, the central office includes baseband processors 202 thatgenerate baseband symbols in resource blocks for transmission to remotesites. In an embodiment, the baseband processors 202 compress theresource blocks as illustrated in FIG. 3 to form compressed blocks.

At block 804, the compressed baseband resource blocks are transmitted toremote sites. For example, the central office 102 uses interface 204 totransmit the resource blocks to the remote site 104 using thetransmission lines 118.

At block 806, the compressed resource blocks are received at remotessites. For example, the compressed resource blocks 112 are received atthe remote site 104 by interface 206.

At block 808, the received compressed resource blocks are processed atthe remote site by the second baseband processing section 106. Forexample, the compressed resource blocks 112 are processed by thedownlink decompressor 208. In an embodiment, the decompressor 208comprises a symbol mapper 504 that maps the received symbols based onmodulation order.

At block 810, the gain of the mapped symbols is adjusted. In anembodiment, the decompressor 208 comprises a gain table 502 andmultiplier 506 that adjust the gain of the mapped symbols.

At block 812, beamforming or antenna mapping is performed to generatefrequency domain baseband signals. For example, the vector processor ormultiplier 508 performs this operation. The frequency domain basebandsignals 510 then flow into a downlink front end 512.

At block 814, the downlink front end performs antenna calibration and/orscaling based on the configuration parameters 304. For example, theblock 602 performs this function.

At block 816, the downlink front end performs subcarrier mapping basedon the configuration parameters 304. For example, the block 604 performsthis function.

At block 818, the downlink front end performs an inverse transform andadds a cyclic prefix based on the configuration parameters 304 togenerate time domain signals 514 for transmission. For example, theblock 606 performs this function.

Thus, the method 800 operates to perform downlink baseband compressionin accordance with exemplary embodiments of a downlink transmissionsystem. It should be noted that the operations of the method 800 can bemodified, added to, deleted, rearranged, or otherwise changed within thescope of the embodiments.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art that,based upon the teachings herein, changes and modifications may be madewithout departing from the exemplary embodiments of the presentinvention and its broader aspects. Therefore, the appended claims areintended to encompass within their scope all such changes andmodifications as are within the true spirit and scope of this exemplaryembodiments of the present invention.

What is claimed is:
 1. A method, comprising: receiving compressed packets over a transmission medium from a central office, wherein the central office performs a first portion of baseband processing to generate the compressed packets from downlink data; receiving configuration parameters; performing a second portion of baseband processing to decompress the compressed packets using the configuration parameters to generate the downlink data; and transmitting the downlink data.
 2. The method of claim 1, wherein the operation of receiving comprises receiving a header for each of the compressed packets.
 3. The method of claim 2, wherein the operation of receiving comprises receiving an antenna index, packet time stamp, and (frame:slot:symbol) number in each header.
 4. The method of claim 1, wherein the operation of receiving comprises receiving frontend configuration parameters for each of the compressed packets.
 5. The method of claim 1, wherein the operation of receiving comprises receiving subcarrier data in each header.
 6. The method of claim 5, wherein the operation of receiving comprises receiving transmit data comprising one or more symbols as part of the subcarrier data in each header.
 7. The method of claim 6, wherein the operation of receiving comprises receiving at least one of a group descriptor, beam index, antenna index, gain index, and modulation order parameter as part of the subcarrier data in each header.
 8. The method of claim 7, wherein the operation of performing comprises utilizing the modulation order parameter and the data to perform symbol mapping to generate mapped symbols.
 9. The method of claim 8, wherein the operation of performing comprises accessing a gain lookup table using the gain index to determine a gain parameter.
 10. The method of claim 9, wherein the operation of performing comprises multiplying the mapped symbols with the gain parameter to generated gain adjusted symbols.
 11. The method of claim 10, wherein the operation of performing comprises performing at least one of vector multiplying or beamforming on the gain adjusted symbols to generate frequency domain baseband samples associated with one or more antennas.
 12. The method of claim 11, wherein the operation of performing comprises processing the frequency domain baseband samples to generate time domain antenna samples associated with the one or more antennas.
 13. The method of claim 12, further comprising performing at least one of antenna scaling, subcarrier mapping, and inverse Fourier transform functions on the frequency domain baseband samples based on the frontend configuration parameters to generate the time domain antenna samples.
 14. The method of claim 13, wherein the operation of transmitting the downlink data comprises transmitting the time domain antenna samples using the one or more antennas.
 15. The method of claim 14, wherein the operation of transmitting comprises transmitting the time domain antenna samples using one of 4G, 5G, and Wi-Fi transmission formats.
 16. An apparatus, comprising: an interface that receives compressed packets and configuration parameters over a transmission medium from a central office, wherein the central office includes a first baseband processing section that generate the compressed packets from downlink data; and a second baseband processing section that decompresses the compressed packets using the configuration parameters to extract the downlink data; and a radio frequency (RF) interface that transmits the downlink data in downlink transmissions from one or more antennas.
 17. The apparatus of claim 16, wherein the configuration parameters comprise: a header that includes an antenna index, packet time stamp, and (frame:slot:symbol) number; frontend configuration parameters; and transmit data comprising one or more symbols and at least one of a group descriptor, beam index, antenna index, gain index, and modulation order parameter.
 18. The apparatus of claim 17, wherein the first baseband processing section comprises: a symbol mapper that utilizes the modulation order parameter and the data to perform symbol mapping to generate mapped symbols; a gain lookup table that outputs a gain parameters based on the gain index; and a multiplier that multiplies the mapped symbols with the gain parameter to generated gain adjusted symbols.
 19. The apparatus of claim 18, wherein the first baseband processing section comprises: a vector processor that performs at least one of vector multiplying or beamforming on the gain adjusted symbols to generate frequency domain baseband samples; and. at least one of antenna scaling circuit, subcarrier mapping circuit, and inverse Fourier transform circuit that process the frequency domain baseband samples based on the frontend configuration parameters to generate time domain antenna samples.
 20. The apparatus of claim 19, wherein the a radio frequency (RF) interface transmits the time domain antenna samples from the one or more antennas using one of a 4G, 5G, or Wi-Fi transmission format. 